Linear compressor with sensor

ABSTRACT

Disclosed herein is a linear compressor having a sensor for detecting the position of a piston. The linear compressor has a position-detecting unit for detecting the position of a piston. The position-detecting unit comprises a sensor core mounted such that the sensor core can be moved along with the piston and the position of the sensor core can be adjusted, and a sensor having a detection hole formed therein for detecting the position of the sensor core disposed in the detection hole. The sensor is fixed to a fixing frame. The sensor core is engaged with a core-supporting member in such a manner that the height of the sensor core can be adjusted without using washers for adjusting the height of the sensor, whereby productivity is improved and manufacturing costs are reduced.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 2004-36266, filed on May 21, 2004 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a linear compressor, and, more particularly, to a linear compressor having a sensor for detecting the position of a piston.

2. Description of the Related Art

Generally, a compressor is part of a refrigerating cycle that is used to generate conditioned air through the circulation of a coolant in an air conditioner or a refrigerator. Specifically, the compressor serves to compress the coolant at high temperature and high pressure. One kind of compressor is a linear compressor, which has a linear motor driven through the interaction due to change in direction of magnetic flux for reciprocating a piston.

FIG. 6 is a sectional view showing a conventional linear compressor. As shown in FIG. 6, the linear compressor comprises a hermetically sealed container 101, a compressing unit 103 for compressing a coolant, and a driving unit 105 for generating power.

The compressing unit 103 includes a cylinder block 111 forming a compression chamber 112, a piston 110 disposed in the compression chamber 112 such that the piston 110 can be reciprocated in the compression chamber 112, and a cylinder head 113 provided at the lower part of the cylinder block 111. The cylinder head 113 has a coolant-introducing chamber (not shown) and a coolant-discharging chamber (not shown) defined therein. Between the cylinder block 111 and the cylinder head 113 is disposed a valve gasket 114 for preventing a coolant from leaking.

The driving unit 105 includes an inner core 115 surrounding the outside of the cylinder block 111, an outer core 119 securely fixed to a fixing frame 117 in such a manner that the outer core 119 surrounds the outer circumference of the inner core 115 while the outer core 119 is spaced a prescribed distance from the inner core 115, the outer core 119 having a coil 145 wound therein, and a permanent magnet 118 mounted between the inner and outer cores 115 and 119 in such a manner that the permanent magnet 118 is vertically reciprocated by means of its electromagnetic interaction with magnetic fields of the inner and outer cores 115 and 119.

To the upper end of the piston 110 of the compressing unit 103 is attached a moving member 123, part of which is disposed between the inner and outer cores 115 and 119 of the driving unit 105 for securely supporting the permanent magnet 118. The moving member 123 is vertically reciprocated as the permanent magnet 118 is vertically reciprocated. Consequently, the piston 110 is vertically reciprocated in the compression chamber 112.

To the upper part of the fixing frame 117, to which the outer core 119 of the driving unit 105 is securely fixed, are mounted plate springs 140 for increasing a vertical reciprocating force of the piston 110.

At a prescribed position of the fixing frame 117 adjacent to the moving member 123 is disposed a sensor 130 for detecting a reciprocating movement of the piston 110. The sensor 130 detects a vertical reciprocating movement of the moving member 123 integrally attached to the piston 110 to measure the position of the piston 110 and the stroke amount of the piston 110, by which the performance of the compressor is verified. The stroke amount of the piston 110 is adjusted to control the discharge amount of the coolant.

The sensor 130 is fixed to a sensor-supporting member 131 by means of a sensor-fixing member 132. Between the sensor 130 and the sensor-supporting member 131 are disposed washers 135. The upper end of the sensor 130 is formed in the shape of a cylinder, and has a detection hole 133 vertically formed therein. In the detection hole 133 is disposed a hollow sensor core 120, which is fixed to the moving member 123. The sensor core 120 is supported by means of a core-supporting member 121. The sensor core 120 is forcibly fitted on the core-supporting member 121.

As the moving member 123 is reciprocated, the sensor core 120 fixed to the moving member 123 is also reciprocated in the detection hole 133, by which an AC voltage is generated at a coil (not shown) formed in the sensor 130. The position of the piston 110 is verified on the basis of a value of the generated voltage.

When the linear compressor with the above-mentioned construction is assembled, the number of the washers 135 disposed between the sensor 130 and the sensor-supporting member 131 is adjusted to control the vertical position of the sensor 130 so that the sensor core 120 can be placed at an appropriate position in the detection hole 133 according to the position of the piston 110.

In the conventional linear compressor, however, the required number of the washers 135 is decided only after the liner compressor is completely assembled, and then the sensor 130 is disassembled to mount the required number of the washers 135. As a result, the assembly time is increased, and addition of the washers 135 may be necessary, which leads to increase of the manufacturing costs.

When the washers 135 are mounted in large numbers, on the other hand, the sensor 130 cannot be firmly supported. Consequently, the sensor 130 may be biased, by which the position of the sensor 130 is not correctly detected.

Also, the sensor core 120 is forcibly fitted on the core-supporting member 121 as described above. As a result, the core-supporting member 121 may be bent during assembly. Furthermore, the sensor core 120 may not be easily fixed to a desired position of the core-supporting member 121.

SUMMARY OF THE INVENTION

Therefore, it is an aspect of the invention to provide a linear compressor wherein a sensor core is engaged with a core-supporting member in such a manner that the height of the sensor core can be adjusted without using washers for adjusting the height of the sensor, whereby productivity is improved and manufacturing costs are reduced.

It is another aspect of the invention to provide a linear compressor wherein the sensor core is not forcibly fitted on the core-supporting member but securely fitted on the core-supporting member through the screw engagement of the sensor core and the core-supporting member, whereby deformation of the core-supporting member is prevented, and the core-supporting member is fixed at a desired position.

In accordance with this aspect, the present invention provides a linear compressor having a position-detecting unit for detecting the position of a piston, wherein the position-detecting unit comprises: a sensor core mounted such that the sensor core can be moved along with the piston and the position of the sensor core can be adjusted; and a sensor having a detection hole formed therein for detecting the position of the sensor core disposed in the detection hole, the sensor being fixed to a fixing frame.

The compressor further comprises: a moving member for linearly reciprocating the piston; and a core-supporting member having one end fixed to the moving member, and the sensor core is mounted to the other end of the core-supporting member.

The sensor core is fitted on the core-supporting member through the screw engagement of the sensor core and the core-supporting member.

The sensor core has a female-screw part, and the core-supporting member has a male-screw part engaged with the female-screw part of the sensor core.

The sensor core is provided with an engagement groove so that the sensor core can be easily rotated by means of a tool inserted in the engagement groove.

The engagement groove is formed in a straight line at the upper end of the sensor core.

The sensor core is provided with a stopper wall for preventing the sensor core from being fitted on the core-supporting member above a prescribed distance.

Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a sectional view showing a linear compressor according to the present invention;

FIG. 2 is a front view showing a core-supporting member of the linear compressor according to the present invention;

FIG. 3 is a plan view showing a sensor core of the linear compressor according to the present invention;

FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 3 showing the sensor core of the linear compressor according to the present invention;

FIG. 5 is a front view, partly in section, showing the engagement of the sensor core and the core-supporting member of the linear compressor according to the present invention; and

FIG. 6 is a sectional view showing a conventional linear compressor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiment of the present invention, an example of which is illustrated in the accompanying drawings. The embodiment is described below to explain the present invention by referring to the figures.

FIG. 1 is a sectional view showing a linear compressor according to the present invention. As shown in FIG. 1, the linear compressor comprises a hermetically sealed container 1, a compressing unit 3 for compressing a coolant, and a driving unit 5 for generating power.

The compressing unit 3 includes a cylinder block 11 forming a compression chamber 12, a piston 10 disposed in the compression chamber 12 such that the piston 110 can be reciprocated in the compression chamber 12, and a cylinder head 13 provided at the lower part of the cylinder block 11. The cylinder head 13 has a coolant-introducing chamber (not shown) and a coolant-discharging chamber (not shown) defined therein. Between the cylinder block 11 and the cylinder head 13 is disposed a valve gasket 14 for preventing a coolant from leaking.

The driving unit 5 includes an inner core 15 surrounding the outside of the cylinder block 11, an outer core 19 securely fixed to a fixing frame 17 in such a manner that the outer core 19 surrounds the outer circumference of the inner core 15 while the outer core 19 is spaced a prescribed distance from the inner core 15, the outer core 19 having a coil 45 wound therein, and a permanent magnet 18 mounted between the inner and outer cores 15 and 19 in such a manner that the permanent magnet 18 is vertically reciprocated by means of its electromagnetic interaction with magnetic fields of the inner and outer cores 15 and 19.

To the upper end of the piston 10 of the compressing unit 3 is attached a moving member 23, part of which is disposed between the inner and outer cores 15 and 19 of the driving unit 5 for securely supporting the permanent magnet 18. The moving member 23 is vertically reciprocated as the permanent magnet 18 is vertically reciprocated. Consequently, the piston 10 is vertically reciprocated in the compression chamber 12.

To the upper part of the fixing frame 17, to which the outer core 19 of the driving unit 5 is securely fixed, are mounted plate springs 40 for increasing a vertical reciprocating force of the piston 10. The plate spring 140 are supported by means of spring spacer 41 vertically mounted to the upper end of the fixing frame 17, and connected to the moving member by means of a fixing shaft 25.

At a prescribed position of the fixing frame 17 adjacent to the moving member 23 is disposed a sensor 30 for detecting a reciprocating movement of the piston 10. The sensor 30 detects a vertical reciprocating movement of the moving member 23 integrally attached to the piston 10 to measure the position of the piston 10 and the stroke amount of the piston 10, by which the performance of the compressor is verified. The stroke amount of the piston 10 is adjusted to control the discharge amount of the coolant.

The sensor 30 is fixed to a sensor-supporting member 31 by means of a sensor-fixing member 32. The upper end of the sensor 30 is formed in the shape of a cylinder, and has a detection hole 33 vertically formed therein. In the detection hole 33 is disposed a sensor core 60, which is fixed to the moving member 23. The sensor core 60 is supported by means of a core-supporting member 50.

As the moving member 23 is reciprocated, the sensor core 60 fixed to the moving member 23 is also reciprocated in the detection hole 33, by which an AC voltage is generated at a coil (not shown) formed in the sensor 30. The position of the piston 10 is verified on the basis of a value of the generated voltage.

The structures of the core-supporting member 50 and the sensor core 60 are shown in detail in FIGS. 2 to 5.

Referring to FIG. 2, a male-screw part 55 having a screw thread of a prescribed length (d1) formed at the outer circumference thereof is provided at the upper end of the core-supporting member 50, which is formed in the shape of a cylinder, and a fixing part 51 is provided at the lower end of the core-supporting member 50. The fixing part 51 of the core-supporting member 50 is fixed to the moving member 23. The male-screw part 55 and the fixing part 51 are connected to each other via a supporting part 52, which is formed in the shape of a bar.

Referring to FIGS. 3 and 4, the sensor core 60 is formed in the shape of a cylinder having a through-hole 65 formed therethrough. The sensor core 60 is provided at the upper end thereof with an engagement groove 61 having a prescribed depth (d2). The engagement groove 61 is horizontally formed in a straight line. The through-hole 65 is formed in the shape of a circle having a size sufficient for the male-screw part 55 of the core-supporting member 50 to be inserted into the through-hole 65. Between the bottom of the engagement groove 61 and the lower end of the sensor core 60 on the inside of the sensor core 60 is formed a female-screw part 63 having a prescribed length (d3).

The engagement of the sensor core 60 and the core-supporting member 50 will be described in more detail with reference to FIG. 5. As shown in FIG. 5, the female-screw part 63 of the sensor core 60 is engaged with the male-screw part 55 of the core-supporting member 50, by which the sensor core 60 is coupled with the core-supporting member 50.

The sensor core 60 is rotated by means of a tool, such as a screwdriver, inserted in the engagement groove 61 so that the sensor core 60 reaches an appropriate position. When the sensor core 60 is rotated, the sensor core 60 is vertically moved along the core-supporting member 50. After the sensor core 60 reaches the appropriate position, the rotation of the sensor core 60 is stopped.

On the upper part of the inside of the sensor core 60 is formed a stopper wall 67 having no screw thread formed thereon. Specifically, the stopper wall 67 is formed on the inside of the sensor core 60 above the female-screw part 63. The sensor core is not inserted below a prescribed height when the sensor core is rotated to be fitted on the core-supporting member 50. Consequently, the sensor core 60 is prevented from being placed at an excessively low position.

As apparent from the above description, the present invention provides a linear compressor wherein a sensor core is engaged with a core-supporting member in such a manner that the height of the sensor core can be adjusted without using any adjusting means for adjusting the height of the sensor, whereby the manufacturing process is simplified, and manufacturing costs are reduced. Consequently, productivity is improved.

Furthermore, the sensor core is not forcibly fitted on the core-supporting member but securely fitted on the core-supporting member through the screw engagement of the sensor core and the core-supporting member, whereby deformation of the core-supporting member is prevented, and the core-supporting member is fixed at a desired position.

Although an embodiment of the present invention has been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents. 

1. A linear compressor having a position-detecting unit for detecting the position of a piston, wherein the position-detecting unit comprises: a sensor core mounted such that the sensor core can be moved along with the piston and the position of the sensor core can be adjusted; and a sensor having a detection hole formed therein for detecting the position of the sensor core disposed in the detection hole, the sensor being fixed to a fixing frame.
 2. The compressor according to claim 1, further comprising: a moving member for linearly reciprocating the piston; and a core-supporting member having one end fixed to the moving member, wherein the sensor core is mounted to the other end of the core-supporting member.
 3. The compressor according to claim 2, wherein the sensor core is fitted on the core-supporting member through the screw engagement of the sensor core and the core-supporting member.
 4. The compressor according to claim 3, wherein the sensor core has a female-screw part, and the core-supporting member has a male-screw part engaged with the female-screw part of the sensor core.
 5. The compressor according to claim 4, wherein the sensor core is provided with an engagement groove so that the sensor core can be easily rotated by means of a tool inserted in the engagement groove.
 6. The compressor according to claim 5, wherein the engagement groove is formed in a straight line at the upper end of the sensor core.
 7. The compressor according to claim 4, wherein the sensor core is provided with a stopper wall for preventing the sensor core from being fitted on the core-supporting member above a prescribed distance. 